1. A very complex question. This is obviously something experts in economics and game theory would argue about, but it’s a common technique that usually works. In more complex cases maybe not. (You could discuss a tax on cigarettes as an example of a tax that probably doesn’t change consumption.)
2. Obviously, yes. It’s a strange question; that’s the basis of economics: to be a producer and not a consumer.
3. Yes.

I started writing a short explanation here based on basic economics, but it felt long and unnecessary. Just imagine three countries with populations of five people each. Picture the buying and selling there, and you’ll understand the foundations of economics. It doesn’t get any simpler than that.

3. I answered yes, assuming the incentive for local production actually works.

David S., local production is certainly not always optimal. I, for example, focus on specializing in one field in which I am a producer, and I import from the supermarket all the other things. If I tried to produce shoes, bananas, and wall plaster for myself on my own, my well-being would unquestionably suffer.

Pini,
Obviously. I thought about explaining exactly that, but it’s just ridiculous; this isn’t a responsa forum on economics, and it doesn’t help the main point.

We’re talking about a struggle between great powers that both produce almost everything. There’s no doubt that some things are more economical to import. But a general policy of encouraging an increase in domestic output is certainly the right step (I’m not addressing the question of whether the particular incentive Trump chooses would be the right one).

When you come to the negotiating table, you want to come with as many things to offer as possible. You’ll choose whether to offer bananas and shoes or something else, but of course you’ll want to arrive with as much capital as possible.
Let’s do a reduction to absurdity: encourage only imports, and you’ll come to the table with nothing but a big smile and nothing to offer in exchange for the imports.